For these ecomodernists, progress requires respectful engagement with a diversity of voices and ideas. "Too often discussions about the environment have been dominated by the extremes, and plagued by dogmatism, which in turn fuels intolerance," they write.

Yet their call for respectful debate and critical reflection has been met with intense hostility by many of their counterparts on the left. At Climateprogess.org, the blogger Joseph Romm dismissed the manifesto as an Orwellian time waster and encouraged his readers to skip any discussion of its ideas. In her book, Klein writes that ecomodernists are either "dishonest or delusional," as they advocate a "doubling down on exactly the kind of reckless, short-term thinking that got us into this mess."

In a recent essay at Aeon magazine, the Duke University law professor Jedediah S. Purdy accused ecomodernists of being nothing more than "branding opportunists," sloshing "around old plonk in an ostentatiously shiny bottle," all in an effort to win speaking and consulting fees.

In a blog post last year, the philosopher Clive Hamilton, of Charles Sturt University, in Australia, declared that by promoting the possibility of the "good Anthropocene," ecomodernists are "unscientific and live in a fantasy world of their own construction." In Earth Island Journal last month, he dismissed the recent manifesto as "detached and dreamy, and blind to the hard truths of political combat."

On the road to managing the many threats we face in the Anthropocene, grassroots activism and political reforms are important, as is the quest for a more advanced arsenal of technological options and a reconsideration of our economic goals. But so too is investment in our capacity to learn, discuss, question, and disagree in ways that constructively engage with uncomfortable ideas.

Yet most academics and journalists avoid challenging the powerful forms of groupthink that have derailed our efforts to combat climate change. In this regard, attacks on those who question cherished assumptions have had a powerful chilling effect. We therefore depend on risk-taking intellectuals like the ecomodernists to lead the way, identifying the flaws in conventional wisdom, and offering alternative ways of thinking and talking about our environmental future.

In such roles, argued Michel Foucault, the function of the intellectual is to "question over and over again what is postulated as self-evident, to disturb people’s mental habits, the way they do and think things, to dissipate what is familiar and accepted, to re-examine rules and institutions."

Conversely, as the sociologist Amitai Etzioni has warned, in the absence of risk-taking intellectuals challenging assumptions, those working on complex problems like climate change may "be lacking in reality testing, be slower in adapting … policies and viewpoints to external as well as domestic changes, and be more ‘ideological.’"

Reading Klein, it is clear that she is not confident that the mass movement she calls for and the deep structural reforms that "change everything" are achievable. Instead, like radical intellectuals of movements past, her utopian vision serves an important political function, creating space for the more pragmatic, less revolutionary ideas of the ecomodernists and others.

With the 2016 US elections on the horizon, ecomodernists are "providing arguments for people in the middle to hold on to so they can have some kind of environmental vision," Paul Robbins, director of the Nelson Institute for Environmental Studies at the University of Wisconsin at Madison, told Slate. "You’ve got to have some kind of position, and they’re offering them something to jump at. It’s not like they’re going to jump on Naomi Klein’s bandwagon."

In navigating a path forward on our tough, new planet, our success depends on constructively grappling with diverse perspectives. Through this approach we can hold our own convictions and opinions more lightly, pursuing the very best of the many ideas available.